An advanced application of the quantitative structure–activity relationship concept in electrokinetic chromatography of metal complexes

Abstract

The relevance of the quantitative structure-activity relationship (QSAR) principle in MEKC and microemulsion EKC (MEEKC) of metal-ligand complexes was evaluated for a better understanding of analyte migration mechanism. A series of gallium chelates were applied as test solutes with available experimental migration data in order to reveal the molecular properties that govern the separation. The QSAR models operating with n-octanol-water partition coefficients or van der Waals volumes were found to be valid for estimation of the retention factors (log k') of neutral compounds when using only an aqueous MEEKC electrolyte. On the other hand, consistent approximations of log k' for both uncharged and charged complexes in either EKC mode (and also with hydro-organic BGEs) were achievable with two-parametric QSARs in which the dipole moment is additionally incorporated as a structural descriptor, reflecting the electrostatic solute-pseudostationary phase interaction. The theoretical analysis of significant molecular parameters in MEKC systems, in which the micellar BGE is modified with an organic solvent, confirmed that concomitant consideration of hydrophobic, electrostatic, and solvation factors is essential for explaining the migration behavior of neutral metal complexes.

Recent developments in the methodology and application of MEEKC

“…78 for the analysis of platinum (II) and platinum (IV) complexes which are used in anticancer drugs. The migration behaviour and Log P ow , which reflects the uptake of such metal complexes into the cell, has previously been described in MEEKC 79, 80. Coupling MS to element specific ICP resulted in enhanced sensitivity and selectivity.…”

Twenty‐one years of microemulsion electrokinetic chromatography (1991–2012): A powerful analytical tool

“…octanol‐water partition coefficient (log P ), are relevant and useful in the assessment of a drug's bioactivity. In recent years, extensive research efforts have been made in MEEKC for the determination of log P . Log P enabled its use for compound hydrophobicity assessment and could be calculated by:where a , b, and k represent the slope, intercept, and capacity factor, respectively.…”

Micellar electrokinetic chromatography: A practical overview of current methodological and instrumental advances

“…Although an appreciable number of articles have been reported to date in MEKC, more study is needed to turn these possibilities into the realization of reliable and robust models for compounds of diverse structures. In this context, it is noteworthy to point out the use of multiple linear regression and artificial neural networks to predict the migration factors of benzene derivatives in MEKC 129, as well as of other correlation algorithms 130, 131.…”